private void detach_course_students(course_student entity)
 {
     this.SendPropertyChanging();
     entity.student = null;
 }
 private void attach_course_students(course_student entity)
 {
     this.SendPropertyChanging();
     entity.student = this;
 }
 partial void Updatecourse_student(course_student instance);
 partial void Deletecourse_student(course_student instance);
 partial void Insertcourse_student(course_student instance);